Isolation of marine xylene-utilizing bacteria and characterization of Halioxenophilus aromaticivorans gen. nov., sp. nov. and its xylene degradation gene cluster

Abstract

Seven xylene-utilizing bacterial strains were isolated from seawater collected off the coast of Japan. Analysis of 16S rRNA gene sequences indicated that six isolates were most closely related to the marine bacterial genera Alteromonas, Marinobacter or Aestuariibacter. The sequence of the remaining strain, KU68F^T, showed low similarity to the 16S rRNA gene sequences of known bacteria with validly published names, the most similar species being Maricurvus nonylphenolicus strain KU41E^T (92.6% identity). On the basis of physiological, chemotaxonomic and phylogenetic data, strain KU68F^T is suggested to represent a novel species of a new genus in the family Cellvibrionaceae of the order Cellvibrionales within the Gammaproteobacteria, for which the name Halioxenophilus aromaticivorans gen. nov., sp. nov. is proposed. The type strain of Halioxenophilus aromaticivorans is KU68F^T (=JCM 19134^T = KCTC 32387^T). PCR and sequence analysis revealed that strain KU68F^T possesses an entire set of genes encoding the enzymes for the upper xylene methyl-monooxygenase pathway, xylCMABN, resembling the gene set of the terrestrial Pseudomonas putida strain mt-2.